Stock feed apparatus

ABSTRACT

Stock-feeding apparatus of the intermittent reciprocating type having a simplified four-way valve for positive control of the sequencing of the apparatus. Particular features include a pressure-operated momentum-absorbing device and a practical simplified stock-release means.

United States Patent '2 I66 245 243 w? I82 [56] References Cited UNITEDSTATES PATENTS 3,038,647 6/1962 Grimm 226/159 3,326,438 6/1967Dickerman.... 226/150 3,429,493 2/1969 Lehmann 226/150 3,462,056 8/1969Scribner 226/ 150 Primary Examiner-Richard A. Schacher Attorney-JosephWeingarten ABSTRACT: Stock-feeding apparatus of the intermittentreciprocating type having a simplified four-way valve for positivecontrol of the sequencing of the apparatus. Particular features includea pressure-operated momentum-absorbing device and a practical simplifiedstock-release means.

llllllhll'Ei- PATENTEUMAYZSIHYI 3580.449

SHEET 1 BF 4 INVENTOR MICHAEL J. CHABAN,JR.

AT'I ORNEYS PATENTED HAYZ 512m SHEET 3 BF 4 MICHAEL INVENTOR J. CHABAN,JF

ATTORNEYS PATENTEDMAY25|971 7 3580.449

SHEET U UF 4 I4 26 ll 222 234 FIG. 6 INVENTOR MICHAEL J- CHABAN, JR.

ATTORNEYS srocx FEED APPARATUS FIELD OF THE INVENTION This inventionrelates in general to automatic feeding apparatus of the intermittentreciprocating type for feeding elongated stock to a cyclically operatingwork machine and more particularly concerns a novel pneumatic mechanismwhich feeds increments of stock in a positive and reliable manner withhighly accurate repetitiveness at a reduced noise level. A simplifiedmeans for releasing the stock speeds the loading and unloading of thisstock-feeding apparatus.

DISCUSSION OF THE PRIOR ART Many manufacturing operations requireintermittent feeding of strip material to a parent work machine such asa punch press which intermittently performs such operations as blanking, cutting, punching and stamping. The length of material to be fed tothe parent machine will vary with the type of operation being performed.The operation of the stock-feeding mechanism is controlled by theoperation of the parent machine so that its speed of operation is insynchronism with the cyclic operation of the punch press. For economicalreasons, it is desirable that the stock-feeding mechanism be able tooperate reliably at least as fast as the maximum operating frequency ofthe parent machine.

Some presently available stock-feeding mechanisms have shown a tendency,when operating at a relatively high frequency, to allow a slightinertial sliding of the stock at the end of each feeding stroke due tothe abrupt stop of the feeding mechanism. Furthermore, at highfrequencies the intensity of the noise. generated by many of the priorstock-feeding mechanisms has been quite high and, with the already highnoise level likely to exist in a machine shop, adds considerably to thediscomfort of personnel in the area.

Wear of the fluid seals in some of the existing stock-feeding mechanismshas resulted in a reliability problem. Resilient rings have generallybeen used to provide seals between members which move relative to oneanother for the purpose of preventing leakage of the prime mover fluid.However, the wear of these seals caused by continued use of the stockfeeder requires their relatively frequent replacement, resulting inuneconomical idleness of the parent machine each time replacement ofthese seals is necessary. Another problem present in many prior devicesis that when the stock is initially loaded into the stock-feed mechanismor removed therefrom, it has been necessary to disconnect or turn offthe source of power, usually by closing a valve in the incoming fluid orair line to the feeding mechanism. This, of course, decreases theproductive time of the machinery while at the same time requiringsignificant manipulation by the operator. Another time-consumingoperation which, in some of the present stock feeders, decreases theproductivity of the parent machine is the adjustment required forvarying the length of each feed stroke. Such existing stock-feedingmechanisms require stopping the work machine, loosening of one or morebolts on the feeding apparatus, moving a bracket which acts as a stopfor the moving feed member and retightening the bolts. This onlyprovides for major stepwise feed stroke adjustment, and anotheroperation is required for minor adjustments between the major adjustmentpositions.

SUMMARY OF THE INVENTION Most existing stock-feeding mechanisms have oneor more of the above-enumerated disadvantages. It is a primary object ofthis invention to provide an incremental stock feeder which permits thestock material to be changed or adjusted without disconnecting the powersource, and which feeds predetermined lengths of stock to a work machinein a positive and accurate manner with a minimum of noise. Furthermore,the length of the feed stroke is continuously adjustable while themachine is operating.

Broadly speaking, the present invention concerns afluidpressure-operated intermittent stock-feeding apparatus capable ofoperating reliably at high speeds with a relatively low air pressureinput. The apparatus generally comprises a stationary body havingstock-clamping means and a reciprocating feed head having stock-grippingmeans. Piston rods and pistons are fixed relative to .the stationarybody with the feed head sleeved onto them. A control valve is mounted inthe stationary body and controls the supply of fluid pressure to thevarious parts of the apparatus.

The stock-feeding apparatus is constructed with novel seals which are acombination of self-lubricating plastic glide rings enclosingconventional resilient O-rings, customarily made of neoprene. The gliderings provide the bearing surfaces for those seals which are subject tosubstantial sliding contact. These combination seals result insubstantially increased reliability and operating life of the apparatus.A braking piston operated by fluid pressure directed by the controlvalve has a rod which extends outwardlyfrom the stationary body and isadapted to be contacted by the feed head near the end of the feedstroke, thereby absorbing most of the momentum of the feed head over ashort distance. This energy-absorbing means essentially eliminates thechance for inertial movement of the stock at the end of each feedstroke. The control valve embodied in this invention is a four-way valvewhich alternately provides line pressure to one side of the apparatuswhile exhausting the other, and momentarily supplies both sides withpressure between each changeover from pressure to exhaust. A manuallyoperated release valve is connected to one side of the stock gripper andis adapted to exhaust pressure from the feeding gripper allowing it toopen to facilitate loading and unloading of the stock feed apparatus. Inthis way, the line pressure remains connected to the mechanism whilestock is inserted or removed therefrom. For purposes of adjusting thelength of feed strokes an adjusting piece, with a bumper threadedthereon, is secured to the stationary body to provide for continuousadjustment of the length of the feed stroke.

BRIEF DESCRIPTION OF THE DRAWING The features and advantages of thisnovel reciprocating stock feed apparatus will become apparent from thefollowing detailed description when read in conjunction with theaccompanying drawing, in which: 7

FIG. I is a plan view of the reciprocating stock-feeding apparatus ofthe present invention;

FIG. 2 is an elevational sectional view of the stock-feeding apparatustaken along cutting plane 22 of FIG. I;

FIG. 3 is a sectional plan view taken generally along cutting plane 3-3of FIG. 2;

FIG. 4 is a sectional view taken along cutting plane 4-4 of FIG. 1showing the control valve in normal position;

FIG. 5 is a sectional view similar to FIG. 4 showing the control valvein a second position; and

FIG. 6 is a diagrammatic arrangement showing the fluid passageways andfluid motors and the pressures existing therein when the stock feedingapparatus is in its normal position.

DESCRIPTION OF THE PREFERRED EMBODIMENT The drawing shows one embodimentof this novel stock feeding apparatus in what is herein referred to asnormal position," that is, the position of the feeding apparatus at theend of a feed stroke. FIG. 5 shows the control valve in a secondoperative position different from the normal position. Although themechanism herein described is intended to be operated with compressedair, it may also be adapted for hydraulic fluid operation with theaddition of a simple exhaust sump having a feedback connection to thefluid supply means. Thus, despite the use herein of the terms air" andair pressure" in reference to the prime mover, it should be understoodthat the principles of this invention are not strictly limited to airpressure operation.

The stock-feeding apparatus may be considered as being comprised of twostructural groups; the main structural members and the operating andcontrol members. For purposes of clarity, the details of these twostructural groups are separately described followed by a description ofthe overall operation of the apparatus.

MAIN STRUCTURAL MEMBERS The main structural members generally includereciprocating feed head 11, stationary body 12, the main piston cylinderand rod assemblies (specifically enumerated below) and rear guide 21, asshown in FIGS. 1, 2 and 3. Referring specifically to FIG. 3, parallelpiston rods 13 and 14 pass through feed head 11, extend into bores 15and 16 in stationary body 12, and are anchored therein by means ofsetscrews l7 and 18 respectively. Rear guide 21 is secured to therearward ends of piston rods 13 and 14 by means of screws 22. Feed head11 is slidably mounted on the piston rods by means of bearings 23 and 24circumscribing rod 13 and bearings 25 and 26 circumscribing rod 14.

Piston rod 13 is formed with piston 27 disposed between bearings 23 and24 in feed head 11. A retaining ring 31 is secured to the piston rodnear its forward end and forward of bearing 24. When the feedingapparatus is constructed, rod 13 is inserted into bore 15 in stationarybody 12 until retaining ring 31 resets against shoulder 32. The rod isthen secured in place by setscrew l7. Longitudinal bore 33 extendsaxially through rod 13 from its forward end to transverse bore 34 justforward of piston 27. Forward end of bore 15 is thus in directcommunication with that portion of bore 35 in feed head 11 which isforward of piston 27. O-ring 36 in groove 37 near the forward end of rod13 resiliently contacts the surface of bore 15 to form an airtight sealtherewith. The seal between piston 27 and bore 35 in feed head 11 isprovided by a glide ring 41 which encircles, and is resiliently forcedoutward by, O-ring 42. Bearing 23 seals the rearward end of bore 35around shaft 13 in a manner similar to the seal of piston 27 inside ofthe bore, that is, by means of glide ring 43 and resilient O-ring 45 andO-ring 46.

The glide rings may be made of a suitable long-lasting selflubricatingplastic such as nylon or polytetrafluoroethylene, sold under the duPonttrademark Teflon. The O-rings are a conventional material such asneoprene. The frequent replacement of worn seals which has been a majorsource of reliability problems with existing stock feeders issubstantially reduced by the seals disclosed herein. These glidering-O-ring seals are preferably used in the present mechanism where asubstantial relative sliding motion occurs between two mem bers andwhere an airtight seal must be maintained between them. The seals usedin the invention herein described substantially increase the operatingtime between seal replacements and thereby increase the reliability ofthe apparatus by a significant factor.

Piston 53 on rod 14 is similarly sealed within bore 47 by means ofO-ring 51 and its enclosing glide ring 52, while ring 54 and itsenclosing glide ring 55 seal bearing 25 to rod 14 and enclose therearward end of bore 47. O-ring 56 and its enclosing glide ring 57 sealbearing 26 around shaft 14 and enclose the forward end of the bore. Rod14 is formed with longitudinal internal bore 61 extending from theforward end of the rod to transverse bore 62 positioned rearwardly ofpiston 53. It is thus readily apparent that the forward end of bore 16communicates directly with that portion of bore 47 which is rearward ofpiston 53. O-ring 63 seals rod 14 to bore 16 immediately rearward ofreduced diameter portion 64 of the rod. Retaining ring 65 is fixed torod 14 and abuts shoulder 66 on stationary body 12 in a manner similarto retaining ring 31 on rod 13.

As shown in FIGS. 1 and 2, adjusting rod 71 is threadedly engaged withstationary body 12 and is prevented from unintentional rotational motionby means of roll pin 72 which extends through the forward end ofadjusting rod 71 and upright portion 73 of stationary body 12. Thecentral portion of adjusting rod 71 passes freely through bore 74 inupright portion 75 of feed head 11. Reduced diameter portion 79 ofbumper element 77 fits partially within internally threadedfeedlength-adjusting piece 76. This bumper is made of a suitable longlasting, resilient, shock-absorbing material such as nylatron. Adjustingpiece 76 and bumper 77 are fixed on adjusting 71 at any desired pointrearward of facing 92 on feed head 11 by means of jamnut 78.Feed-length-adjusting piece 76 has an externally knurled portion tofacilitate manual longitudinal adjustments afterjamnut 78 has beenloosened. Adjusting piece 76 is also provided with hexagonal portion 81adapted to be engaged by a wrench to hold the adjusting piece in placewhile jamnut 78 is being tightened against it or when it is beingdisengaged therefrom.

Rear guide 21 is formed with channel 82 adapted to slidingly engageslotted guide member 83 having front stock guide 84 formed thereon.Guide member 83 is secured to rear guide 21 by means of screw 85 whichis threadedly engaged with rear guide 21. By looseningscrew 85 guidemember 83 may be slid in groove 82 so that front stock guide 84 makeslight contact with the front edge of stock of various widths. The backedge of the stock, as defined by stock line SL in FIGS. 1 and 2,contacts wear pins 86 and 87 on feed head 11 and stationary body 12respectively. In this manner, the path which the stock must take as itpasses through the stock-feeding apparatus is accurately defined.

Feed head 11 is provided with cutout area 91 at the rearward end ofupright portion 75 to define vertical facing 92 which makes contact withbumper 77 at the end of each indexing stroke of the feed head.Stationary body 12 is shown with an identical cutout area and verticalface, primarily to enable each of the main structural portions 11 and 12of the apparatus to be made from the same basic castings, if desired. Byusing the same castings, a substantial savings is realized in thepreliminary formation of these body members.

The flow of air throughout the stock-feeding apparatus is controlled bya control valve which is located in bore 93 in stationary body 12. Thevalve is formed with a stem 94 extending above vertical section 73 ofstationary body 12 and is fitted with a slidable cap 95. The line airpressure may be fed to either the front or back of stationary body 12and is shown in FIG. 1 connected by suitable conventional fitting 96 tothe back of the stationary body. Fitting 96 may be connected to tappedhole 97 at the back or tapped hole 98 at the front of stationary body 12(shown in FIG. 3).

Operating and Control Members The operating and control membersgenerally comprise the control valve, the gripping and clamping pistons,the braking piston and the release valve, shown in FIGS. 2, 3 and 4.Control valve 90 resides in bore 93 which passes entirely throughstationary body 12 including upright portion 73 thereof Control valvebearing 101 is a sleeve having a closed lower end 102 and is equal inlength to bore 93 in which it is mounted. Annular grooves 103, 104 and105 are provided at predetermined spaced intervals around the exteriorof bearing 101, each of said grooves being in communication with thebearing interior by means of a plurality of holes 106, 107 and 108respectively, spaced around each groove. With this construction, bearing101 may be inserted within bore 93 without regard for rotationalalignment. Snap ring 11 1 fits within groove 112 near the top of bearing101 to limit the upward travel of the control valve.

Control valve 90 is formed with piston 114 at its lower end, piston 1 15spaced therefrom and enlarged portion 116 spaced a short distancefarther beyond piston 115. Enlarged portion 116 abuts snap ring 111 whenthe valve is in its upper, or normal, position. Above enlarged portion116 is stem 94 topped by another enlarged portion 117. Each piston ishermetically and slidably sealed within bearing 101 by means of gliderings and O-rings in a manner similar to that with which main pistons 27and 53 are sealed within their respective bores 35 and 47. Axial bore127 and counterbore 128, having a transitional shoulder 131therebetween, are formed in control valve 90. A compression spring 132is located within axial counterbore 128, one end abutting shoulder 131and the other end supported by lower end 102 of bearing 101. This springbiases control valve 90 upwardly, its upward movement being limited bysnap ring 111 in contact with enlarged portion 116. Enlarged portion 116is formed with diametrically opposed arcuate longitudinal grooves 133.These grooves provide communication to the atmosphere for ore 127 andcounterbore 128, through transverse bore 135 and annular area 134surrounding the valve between enlarged portion 116 and piston 115. It isimmediately apparent from the above description that the lower portionof bearing 101 below piston 114 is always exhausted to atmosphere.

Control valve 90 is also provided with upper axial ore 136 in which isaxially disposed compression spring 137. The upper end of spring 137 isseated in depression 141 in cap 95. The upward movement of cap 95 islimited by snap ring 142 which ears against the lower surface ofenlarged area 117 of the valve stem. Spring 137 is normally stiffer thanspring 132 so that when downward force is applied to the top of cap 95valve 90 moves downward within bearing 101 before cap 95 moves withrespect to the valve stem. The significance of this operation will bediscussed below under Details of Operation.

With specific reference now to FIG. 2, independent pistons 151 and 164are shown mounted for reciprocating movement in feed head 11 andstationary body 12 respectively. These pistons operate the stock gripperan clamp in response to air pressure selectively supplied by the controlvalve. Piston 151 and its connected gripper rod 152 are sealed to theside of bore 153 and an airtight seal between bearing and bore isprovided by O-ring 155. Accidental removal of the bearing is preventedby snap ring 156 residing in groove 157 in the feed head. O-ring 161 and162 provide slidable airtight seals between piston 151 and ore 153 androd 152 and bearing 154 respectively. Although the glide ring-O-ringcombination could be used for sealing piston 151 and gripper rod 152, 0-rings have proved satisfactory for this purpose because of the verysmall distance which the piston moves, this distance being in the orderof 0.050 inch or less, depending upon stock thickness. The resultingsliding friction is so small that wear is not a factor with thesepistons. In order to improve the speed of response of piston asignificant portion of the space between the piston and the bottom ofore 153 is occupied by piston extension 163. With the volume which mustbe occupied by the primemover thus decreased, the opening below piston151 fills significantly faster than it otherwise would and the responsetime of the piston is commensurately decreased. A leaf spring 168 issecured to feed head 11 by means of screw 169 and engages notch 170 inthe top surface of gripper rod 152. This leaf spring biases piston 151downward just enough to overcome friction, while at the same timeproviding a ramp to facilitate the insertion of strip material into themechanism between rear post 158 and gripper rod 152.

Piston 164 and clamping rod 165 are similarly sealed within bore 166 instationary body 12. Bearing 167 is sealed against bore 166 by means ofOring 171 and is maintained in position by means of snap ring 172.Piston 164 is sealed against the side of bore 166 by means of O-ring 173while clamping rod- 165 is sealed against the side of caring 167 bymeans of O-ring 174. Piston 164 is similarly constructed with extension163 on piston 151.

Rear post 158 extends outwardly from upright portion 75 of feed head 11toward the front of the mechanism and presents a linearly curved surface1580 against which the stock is held by means of the flat upper surfaceof gripper rod 152. Rear post 158 is secured within bore 750 (seeFIG. 1) in a suitable manner such as by means of setscrew 158b. Forwardpost 159 is secured within ore 73a in upright portion 73 of body 12 bymeans of setscrew 160. It, too, presents a lower linearly curved surface159:: against which the stock is clamped by means of the upper flatsurface of clamping rod 165. The portion of forward post 159 within bore73a is configured differently than is rear post 158, for reasonswhichwill be explained later.

Existing machines which use fiat surface contact for gripping the stockare subject to feed length irregularities due to variations in thethickness of most stock. With the stock feeder herein disclosed,however, the flat surface of each rod contacting the rounded side ofeach post results in line contact with the stock, thereby creating aroper grip unaffected by surface roughness or irregularities in thestock thickness.

Near the end of each feeding stroke, feed head 11 contacts piston rod176 which is connected to braking piston 177 mounted within bore 181 instationary body 12. Bearing 182 is sealed against the side of bore 181by meansof O-ring 183 and is prevented from being accidentally removedfrom the bore by means of snap ring 184. The proper seal between piston177 and bore 181 is provided by O-ring 185 and glide ring 1850 while theseal between bearing 182 and piston rod 176 is provided by O-ring 186.Piston rod 176 protrudes from stationary body 12 and its rearward end187 makes contact with the forward facing of feed head 11 just prior tothe end of each feeding stroke. Due to pressure which forces piston 177rearwardly, the velocity of feed head 11 is sharply reduced just priorto the end of its forward travel. The air in the chamber forward ofpiston 177 is forced through a small orifice under the momentum of thefeed head so that the air pressure existing in the apparatus absorbs thekinetic energy of the feed head and prevents it from stopping tooabruptly.

With the feeding mechanism shown in its normal position in FIG. 2, thestock is held tigh'tly between gripper rod 152 and rear post 158.Loading and unloading of the mechanism is facilitated by means ofrelease valve 191 connected to the chamber below piston 151 by means ofpassage 201. This valve is hand operated and is simply pressed upwardwhenever it is desired to release the stock from the rear gripper. Inits normal condition, release valve 191 is biased downward by airpressure and returns to normal position when released by a combinationof the force of gravity and the trapped compressed air in bore 192 abovethe valve. The release valve is sealed for sliding motion to the side ofbore 192 by means of O-ring 194. Valve stem 195 has a flat cutout area196 through which the pressure at the base of piston 151 is releasedwhen the valve is moved upward. The valve stem has a second flat area197 above O-ring 194 on the forward side of the valve which is normallyin communication with the upper end of ore 192 and with the lower end ofpiston bore 153 by means of the aforesaid passageway 201 and transversehole 198 through valve stem 195. Lip 202 at the upper end of the valvemakes contact with setscrew 193 and prevents release valve 191 fromfalling out of bore 192.

Details of Operation The operation of the structure whose elements havebeen described above will now be set forth in detail. The prime moverwhich is supplied under pressure to the stock-feeding apparatus isdirected through various portions of the apparatus by means ofpassageways under the control of fourway valve 90. It will be assumedfor purposes of this description that the prime mover is air although itcould be any other suitable fluid. The air supply may be connected atthe back of stationary body 412 by means of fitting 96 connected totapped hole 97 to supply air to spool valve 90 through passageway 205.An alternative connection would be to the front of the stationary bodyby means of tapped hole 98 and the air would then be supplied to thespool valve by means of passageway 206.

It is readily apparent from FIGS. 4 and 5 that full line pres surealways exists in the cylindrical area around valve 90 rounding thecentral portion of front post 159 within upright portion 73 ofstationary body 12. The back end of front post 159 is stationarilysecured within upright portion 73 and is sealed against the side of bore73a by means of O-rings 212 and 213. The air pressure in opening 207 iscommunicated to bore forward of main piston rod 13 through verticalpassageway 214 (see FIG. 2) and thence to the upper side of clampingpiston 164 by means of lateral passageway 215 (see FIG. 3). Thispressure is further communicated to bore 181 forward of piston 177 bymeans of orifice 216. From the forward end of bore 15 in stationary body12 the line pressure passes through bore 33 in rod 13 to cylindricalarea 217, between piston 27 and bearing 24, by means of transverse bore34. Passageway 221 in feed head 11 provides communication of thispressure from area 217 to a similar cylindrical area 222 surroundingpiston rod 14 forward of piston 53. This pressure is also communicatedto the bottom of gripping piston 151 by means of passageway 201 and thehole 198 through release valve stem 195.

The crosshatched passageways shown diagrammatically in FIG. 6 indicatethe portions of the mechanism which are normally under full linepressure. It should be noted that control valve 90 and its cap 95 aremaintained in their normal positions by means of springs 132 and 137respectively and that the line pressure between pistons 114 and 115 ofthe valve has no effect upon its position within bearing 101. Withfurther reference to FIG. 6, it is evident that when the stock-feedingapparatus is in its normal condition, stock-clamping piston 164 isbiased downward to an open position, braking piston 177 is biasedrearward toward sliding member 11 in full brak ing position, releasevalve 191 is biased downward and sliding member 11 is biased to itsforward or feeding position.

The other side of the pistons, passageways, and valves, which were notincluded in the foregoing discussion of the portions of the mechanismunder pressure, are exhausted to the atmosphere. The area 223 withinbearing 101 between valve piston 114 and closed end 102 of the bearingis exhausted to the atmosphere through counter bore 128 and bore 127which are axially disposed within valve 90, through transverse bore 135to annular opening 134 and thence to the atmosphere through grooves 133on either side of enlarged portion 116 (FIG. 4). That portion of bore166 in stationary body 12 below clamping piston 164 communicates withthe atmosphere through passageway 224 to area 223 (see FIGS. 2, 3 and6). The portion of bore 16 forward of piston rod 14 is exhausted throughpassageway 225 to the lower portion of bore 166, while bore 181 rearwardof braking piston 177 is exhausted by means of passageway 226 whichopens into bore 16 adjacent the annular area 227 surrounding reduceddiameter portion 64 of rod 14. The portion of feed head main bores 35and 47 rearward of pistons 27 and 53 respectively are interconnected bymeans of passageway 231 and are exhausted to atmosphere throughtransverse bore 62 and longitudinal bore 61 in rod 14, the latter boreopening into the forward end of bore 16 in stationary body 12. The upperside of gripping piston 151 is exhausted to atmosphere by connectionwith passageway 231 through passageway 232. It is thus apparent thatthere is normally no pressure acting upon the bottom of piston 164, thetop of piston 151, the rearward side of braking piston 177, and therearward side of pistons 27 and 53 which would in any way tend tocounteract the line pressure existing on the opposite sides of thesepistons.

When the parent work machine commences its downward stroke it makescontact with cap 95 of valve 90 by suitable means such as an operatingrod (not shown) which forces the cap downward. As shown in FIG. 4,spring 132, which is weaker than spring 137, is compressed by thedownward motion of valve 90 before spring 137 is compressed and beforecap 95 slides downward along stem 94, As valve 90 progresses downward,piston 114 first closes off the exhaust side of the apparatus by closingaccess holes 106 so that passageway 224 no longer communicates withexhaust area 223 below piston 114. Further downward movement of thevalve connects passageway 224, through annular groove 103 and holes 106in bearing 101, to the line pressure existing in the cylindrical portionaround the valve between pistons 114 and 115. At this instant in time,before the side of the mechanism normally under pressure is exhausted,both sides of the apparatus, that is, the entire system, is exposed tofull line pressure. Clamping piston 164 momentarily becomes adifferential piston and is forced upward because the area of the bottomof the piston is greater than the area of the top, both top & bottombeing exposed to the same pressure. The pressure on the upper side ofgripper piston 151, which is also a differential piston for a moment,increases but the piston remains in an upward or closed position becauseof its greater bottom area. Thus, for a fraction of the downward travelof control valve before feed head 11 commences its indexing stroke, bothgripping and clamping members are forced into closed positions andprevent any spurious motion of the stock in the machine. At this pointalso, feed head 1 1 has not yet commenced its indexing motion. Thepressure on the rearward side of the main pistons builds up relativelyslowly due to the special configuration of bearings 23 and 25 in feedhead 11. These bearings are constructed with shoulders 233 and 234respectively which partially block the ends of passageway 231 andtransverse bore 62, as shown in FIG. 3. The resulting metering effectincreases the time required for the pressure on the rearward sides ofpistons 27 and 53 to build up to line pressure, allowing both clampingpiston 164 and gripping piston 151 to be urged upward to grip the stockbefore any movement of feed head 11 occurs. It should be remembered thatat this point in the operating cycle there is some rearward force,although small, on the feed head exerted by braking piston 177 becauseit, too, is a differential piston for the same momentary period in thecycle. It should also be noted that pistons 27 and 53 are notdifferential pistons so that, ignoring other forces which might bepresent, even if the pressure became equal on both sides of thesepistons the feed head would remain in whatever position it was in at thetime the pressure was equalized.

The pressure on the rearward side of braking piston 177 also builds upto line pressure but the piston is still urged in a rearward directionbecause of the pressure on the forward side of the piston which morethan balances the pressure on the opposite side. As the pressure on therearward side of braking piston 177 builds up, the actual force whichpiston rod 176 exerts in the rearward direction upon feed head 11 isdecreased and is more than counteracted by the pressure which stillurges the feed head forward.

.As control valve 90 continues downward to the position shown in FIG. 5,piston 115 passes holes 108 and passageway 211 from bore 73a becomesexhausted to atmosphere through annular groove 105, holes 108, annulararea 134 and exhaust grooves 133. When the control valve reaches thisposition, the entire side of the feed mechanism which was originallyunder line pressure when the mechanism was in normal condition is fullyexhausted to atmosphere while the other side of the mechanism which wasoriginally at atmospheric pressure is now maintained at line pressure.This piston 164 ceases to become a differential piston in actualoperation and is urged upward with even greater force because there isno partial balancing force on the upper side thereof. Similarly, piston151 is urged downward to disengage the stock because of the rapiddecrease in pressure on the lower side of that piston together with thedownward bias of leaf spring 168. Also the forward side of the rakingpiston 177 is exhausted so that piston rod 176 is urged to the left toprevent any spurious force against feed head 11 which might otherwisecause a false start in the indexing direction. As the pressure on theforward side of pistons 27 and 53 is reduced, the line pressure on therearward side of these pistons causes feed head 11 to move in theindexing direction a distance which is controlled by the position ofadjusting piece 76 and bumper 77.

As the parent machine completes its downward movement a distance longerthan the length of travel of valve 90, cap continues downward but in noway further affects the operation or control of the stock feedingmechanism. FIG. shows the control valve at the extent of its downwardtravel with cap 95 having moved downward somewhat with respect to stem94. This dual-spring arrangement of control valve 90 allows the indexingand feeding portions of the stock-feeding mechanism to take placesomewhat independently of the length of travel of the operating head ofthe parent machine. Thus the downward stroke of the parent machine maybe substantially greater than the distance allowed for the travel ofcontrol valve 90 and this additional distance is absorbed by thetelescoping action of cap 95. This arrangement also allows the indexingstroke of feed head 11 to be completed before the stock is actuallyacted upon by the parent machine so as to ensure that the stock isabsolutely stationary when the parent machine performs its function. Itshould be noted that with a given control valve travel distance, anylength of workmachine travel may be accounted for by constructing aproper length valve stem 94 and sliding cap 95.

As the parent machine commences its return to normal position, cap 95first moves upward under the urging of its spring 137 until it reachesits upper limit so that the operating portion of the parent machine isremoved from the work area before control valve 90 is permitted to moveupward under the urging of spring 132. Valve 90 then commences to riseand piston 115 immediately closes off the atmosphere exhaust ofpassageway 211 as it passes holes 108. As the control valve continues torise, piston 115 exposes holes 109 and consequently the side of themechanism which was exhausted on the downward stroke is subjected to theline pressure which always exists around the valve between pistons 114and 115. Once again all the operating portions of the stock-feedingmechanism are momentarily under line pressure and both gripping piston151 clamping piston 164 are urged upward to grip the stock, both onceagain momentarily acting as differential pistons. Braking piston 177 isurged rearwardly in preparation for absorbing the shock of feed head 11at the end of the next feed stroke. The pressure on both sides ofpistons 27 and 53 tends to become equalized but the feed head is noturged forward because there is no resultant forward force. As controlvalve 90 continues upward, passageway 224 becomes exhausted toatmosphere and the mechanism returns to the condition shown in FIGS. 4and 6 so that piston 164 is urged downward, piston 151 is urged upwardand the feed head is urged downward, piston 151 is urged upward and thefeed head is urged forward to perform a feeding stroke.

As feed head 11 moves forward and approaches the end of the feed stroke,it contacts protruding end 187 of braking piston rod 176. As indicatedin FIGS. 2 and 3, orifice 216 is quite small compared with bore 181 sothat the air in bore 181 forward of piston 177 is highly compressedwhile relatively slowly passing through the orifice. Thus the air inbore 181 forward of braking piston 177 is forced through orifice 216 bythe force of feed head 11 on the braking piston but the size of theorifice is such that the braking piston absorbs most of the momentum offeed head 11 before it comes to rest against stationary body 12. It hasbeen found that a ratio in the range of several hundred to one betweenthe area of bore 181 and the area of orifice 216 will provide thedesired braking action of piston 177. Of course, the ratio necessarywill depend upon the air pressure involved and the mass and speed of thefeed head. Bumpers 235 and 236 are provided on the forward face of feedhead 11 to quietly finally halt the feed head and absorb the remainderof its kinetic energy. These bumpers are a suitable long lastingenergy-absorbing material, such as nylatron, similar to bumper 77.

Release valve 191, shown in FIG. 2, is provided to facilitate loadingand unloading the stock-feeding mechanism. When the parent machine isstopped and the stock-feeding mechanism is in normal position asindicated in the drawing, the stock is not clamped between clamping rod165 and forward post 159 but is gripped tightly between gripper rod 152and rear post 158. When the mechanism is in this condition, pressureexists in the release valve bore 192 above flange 241,

thereby forcing valve 191 downward. The actual downward force involvedis not great due to the small cross section of the valve and may beeasily overcome by pressing upward on button 242 at the lower end ofrelease valve 191. As valve 191 travels upward, cutout area 196 becomesaligned with the rearward part of passageway 201 which connects with thelower portion of bore 153, thereby bleeding off the air on the lowerside of piston 151. This allows the piston to drop under the doubleinfluence of gravity and leaf spring 168 so that the stock if free to beremoved or new stock may be inserted into the machine. Stem 105 of therelease valve fits tightly in bore 192, and effectively seals off theforward portion passageway 201 which connects with passageway 221 sothat the remainder of the feeding apparatus remains under pressure as inits normal condition while piston 151 is being exhausted.

From the foregoing description of the operation of this stock-feedingmechanism it is apparent that a definite timed relationship exists andis maintained between the operations of all of thefluid-pressure-controlled parts of the machine. This timed relationshipis maintained by the single four-way control valve 90, which operatesthrough the above described passageways and orifices. This control valveensures that the stock is tightly clamped to the stationary body beforethe feed head starts an indexing stoke and that the stock is grippedsecurely on the feed head before the commencement of a feed stroke. Thevalve provides full pressure on the braking piston in time to absorb themomentum of the feed head at the end of the feed stroke, but urges thebraking piston in the reverse direction just prior to an indexing strokein order to prevent spurious motion of the feed head. This timing is, ofcourse, es-

' sential to the proper and efficient operation of the stock feedapparatus described herein.

As previously mentioned, extensions 163 and 175 of pistons 151 and 164respectively occupy a significant amount of the space in bores 153 and166 beneath their respective pistons. Since this volume is relativelysmall, the pistons react very quickly because the pressure beneath thembuilds up rapidly, thus enhancing the speed at which the stock-feedingsystem may operate. The bottom of each bore 153 and 166 is formed withbosses 242 and 243 respectively to maintain the piston slightly abovethe bottom of their respective bores when they are in the lowerposition. This provides for shorter piston travel and more positivepiston action by allowing the air to readily fill the space beneath thepiston. By maintaining a separation between the piston and the bottom ofthe bore any possibility of a vacuum being formed between two flatsurfaces is eliminated. Threaded holes 224 and 245 are sealed by meansof plugs 246 and 247 respectively. If at any time it is desired toremove the bearings and pistons from bores 153 and 166, plugs 246 and247 may be removed and the bearings and pistons simply pushed outwardsby inserting an elongated tool through these holes.

The stock-feeding apparatus herein described in very efficient and fastacting while being economical to operate and maintain. It can operateeffectively on air pressure in the range of 50-120 p.s.i., with normalpressure being approximately p.s.i. Of course, it can be adapted forfluids and for much higher pressures if desired. In order to facilitatemounting the stock-feeding apparatus on the work machine, holes 251 and252 are provided in stationary body 12 into which suitable mountingmeans such as bolts may be inserted for attachment to the parentmachine. The materials used in the stock-feeding mechanism are for themost part conventional for such a device. The piston rods and valves aregenerally made of tool steel and the bearings are either bronze orsteel. The O-rings are conventional neoprene and the glide rings arenylon, Teflon or other suitable self-lubricating, long lasting plastic.However, feed head 11 and stationary body 12 are made of cast aluminum.With these main body portions being made of aluminum, the entiremechanism is lighter and easier to handle than similar stock-feedingmechanisms which are made entirely of steel or other relatively heavyalloys. Furthermore, since the feed head is relatively light, it is ableto react llll more quickly and positively to the various changes inpressures in the operating portions of the mechanism. Furthermore,energy which braking piston 177 must absorb is substantially reducedthrough the use of aluminum for the feed head. This combination of alight aluminum feed head and the braking piston practically eliminatesany possibility of continued motion of the stock at the end of eachfeeding stroke due to its inertia.

It is to be understood that the above-described preferred embodiment ismerely illustrative of the principles of this invention. For instance,although the drawing shows a dual main piston and cylinder arrangement,it is possible that a single piston and cylinder construction could beused. In such cases a guide bar would be necessary to maintain theattitude of the feed head and both air passages 33 and 61 wouldnecessarily be located within one rod. However, the principles of theinvention would still apply. Furthermore, the bumpers 235 and 236 couldbe mounted on the stationary body as well as on the feed head. Numerousother embodiments may be devised in accordance with these principles bythose skilled this art without departing from the spirit and scope ofthe invention as defined by the appended claims.

What I claim is:

l. A stock-feeding apparatus operable through alternate feed andindexing strokes for incrementally feeding stock to a work-performingmachine in synchronism with the operating cycle thereof, saidstock-feeding apparatus being powered by a fluid prime mover andcomprising:

a stationary body;

a feed head;

means for connecting said feed head to said stationary body forreciprocal rectilinear motion with respect thereto; fluid-pressureoperated means for controlling the rectilinear motion of said feed head;fluid-pressure-operated energy-absorbing means mounted between saidstationary body and said feed head, said energy-absorbing means beingoperable between energyabsorbing and retracted positions; and meansincluding a control valve for controlling the application of fluidpressure to said means for controlling the rectilinear motion of saidfeed head and to said energyabsorbing means;

said control valve providing fluid pressure to said energyabsorbingmeans in timed relationship with the fluid pressure applied to saidmeans for controlling the rectilinear motion of said feed head so thatsaid energy-absorbing means absorbs the kinetic energy of said feed headthrough an incremental distance of the travel of said feed head at theend of said feed stroke.

2. The stock-feeding apparatus recited in claim 1, wherein:

said control valve provides fluid pressure to urge said energy-absorbingmeans to said energy-absorbing position while providing fluid pressureto said means for controlling the rectilinear motion of said feed headto urge said feed head in a feeding direction; and

said control valve provides fluid pressure to urge said energy-absorbingmeans to said retracted position while providing fluid pressure to saidmeans for controlling the rectilinear motion of said feed head to urgesaid feed head in an indexing direction.

3. The stock-feeding apparatus recited in claim 2, wherein:

said stationary body is formed with a cylinder therein;

said energy-absorbing means includes a double-acting piston mounted insaid cylinder and a rod attached to said piston adapted to protruderearwardly from said cylinder toward said feed head.

4. The stock-feeding apparatus recited in claim 3, wherein:

said stationary body if formed with an orifice communicating thepressure from said control valve with the forward end of said cylinder;

said energy-absorbing means is urged to said energy-absorbing positionwhen fluid pressure is supplied to said cylinder forward of said piston;

the kinetic energy of said feed head is absorbed by compression of thefluid in said cylinder and the release of said fluid through saidorifice, the cross-sectional area of said orifice being so related tothe cross-sectional area of said cylinder that a substantial portion ofthe kinetic energy of said feed head is absorbed during the timerequired for the excess pressure in said cylinder to be released throughsaid orifice.

5. A stock-feed apparatus operable through alternate feed and indexingstrokes for incrementally feeding stock to a work-performing machine insynchronism with the operating cycle thereof, said stock-feedingapparatus being powered by a fluid prime mover and comprising:

a stationary body;

a feed head;

means for connecting said feed head to said stationary body forreciprocal rectilinear motion with respect thereto;fluid-pressure-operated means for controlling rectilinear motion of saidfeed head;

the

fluid-pressure-operated stock-gripping means mounted on said feedheadand movable between gripping and releasing positions, saidstock-gripping means being normally in said gripping position;

means including a control valve for controlling the application of fluidpressure to said stock-gripping means in timed relationship with thefluid pressure applied to said means for controlling therectilinearmotion of said feed head; and

a release valve for selectively moving said stock-gripping means to saidreleasing position, said release valve being movable between open andclosed positions and being normally urged to said closed position bysaid fluid pressure, said release valve being formed with a holetherethrough the transmit fluid pressure to said stockgripping meansfrom said control valve when in said normally closed position;

said release valve being shaped and configured to interrupt the supplyof fluid pressure from said control valve to said stock-gripping meansand to exhaust fluid pressure from said stock-gripping means when insaid open position.

6. A stock-feeding apparatus operable through alternate feed an indexingstrokes for incrementally feeding stock to a work-performing machine insynchronism with the operating cycle thereof, said stock-feedingapparatus being powered by a fluid prime mover and comprising:

a stationary body;

a feed head;

means for connecting said feed head to said stationary body forreciprocal rectilinear motion with respect thereto; fluid pressureoperated means for controlling the rectilinear motion of said feed head;

fluid-pressure-operated stock-gripping means mounted on said feed headand movable between gripping and releasing positions;

fluid-pressure-operated stock-clamping means mounted on said stationarybody and movable between clamping and releasing positions; and

means including passageways defining first and second operative sides ofsaid apparatus and a control valve for controlling the application offluid pressure through said passageways to said means for controllingthe rectilinear motion of said feed head, to said stock-gripping meansand to said stock-clamping means;

said control valve providing fluid pressure alternately to said firstand second operative sides and cooperatively with said passagewaysproviding fluid pressure in timed relationship to saidfluid-pressure-operated stockgripping, clamping andrectilinear-motion-controlling means;

said control valve providing fluid pressure to said first operative sidewhen in a first position and providing fluid pressure to said secondoperative side when in a second position;

said control valve further simultaneously applying fluid pressure toboth said first and second operative sides when in a momentary position,said control valve passing through said momentary position each time itpasses between said first and second positions.

7. The stock-feeding apparatus recited in claim 6, wherein:

said stationary body is formed with a control valve bore therein; and

said control valve is a four-way valve mounted for longitudinal movementin said bore and connected with said passageways.

8. The stock-feeding apparatus recited in claim 7 wherein:

said control valve includes a stem mounted one end thereof and a captelescopically mounted on said stem, said stock-feeding apparatusfurther comprising:

first means for continuously biasing said control valve to said firstposition; and

' second means for biasing said cap away from said control valve, saidsecond biasing means being stronger than said first biasing means;

said cap being contacted by said work-performing machine during itswork-performing cycle so as to move said control valve from said firstposition through said momentary position to said second position, saidwork-performing machine then continuing movement in the same directionto perform work on said stock, thereby telescoping said cap on saidstern toward said control valve, said work machine then retracting fromthe vicinity of said stock before said control valve returns to saidfirst position to initiate another cycle of said stock-feedingapparatus.

9. A stock-feeding apparatus operable through alternate feed andindexing strokes for incrementally feeding stock to a work-performingmachine in synchronism with the operating cycle thereof, saidstock-feeding apparatus being powered by a fluid prime mover andcomprising:

a stationary body;

a feed head;

means for connecting said feed head to said stationary body forreciprocal rectilinear motion with respect thereto;fluid-pressure-operated means for controlling rectilinear motion of saidfeed head; fluid-pressure-operated stock-gripping means mounted on saidfeed head and movable between gripping and releasing positions;fluid-pressure-operated stock-clamping means mounted on said stationarybody and movable between clamping and releasing positions; and

means including passageways defining first and second operative sides ofsaid apparatus and a control valve for controlling the application offluid pressure through said passageways to said means for controllingthe rectilinear motion of said feed heads to said stock-gripping meansand to said stock-clamping means;

said control valve providing fluid pressure alternately to said firstand second operative sides and cooperatively with said passagewaysproviding fluid pressure in timed relationship to saidfluid-pressure-operated stockgripping, clamping andrectilinear-motion-controlling means;

said stationary body being formed with a control valve bore therein,said control valve being a four-way valve mounted for longitudinalmovement in said bore and connected with said passageways;

said control valve being formed with a first port connected the to saidfirst operative side of said apparatus, a second port connected to saidsecond operative side, a fluid pressure port and an exhaust port;

said control valve having normal and alternate main posi tions and amomentary position, said control valve passing through said momentaryposition when changing from one main position to the other;

said control valve normally connecting said fluid pressure port to saidfirst port and said exhaust ort to said second port, and alternatelyconnecting said urd pressure port to said second port and said exhaustport to said first port; said control valve connecting said fluidpressure port to both said first and second ports when in said momentaryposition. 10. The stock-feeding apparatus recited in claim 9 wherein:said means for controlling the rectilinear motion of said feed headincludes a double-acting piston assembly having its forward sideconnected to said first operative side of said apparatus and itsrearward side connected to said second operative side .of saidapparatus; said stock-gripping means includes a double-actingdifferential piston assembly having its lower side connected to saidfirst operative side of said apparatus and its upper side connected tosaid second operative side of said apparatus; said stock-clamping meansincludes a double-acting differential piston assembly having its upperside connected to said first operative side of said apparatus and itslower side connected to said second operative side of said apparatus;whereby said feed head is normally urged in a feeding direction, saidgripping means is normally urged to a gripping position and saidclamping means is normally urged to releasing position; whereby saidfeed head is alternately urged in an indexing direction, said grippingmeans is alternately urged to a releasing position and said clampingmeans is alternately urged to a clamping position; and whereby said feedhead remains stationary, said clamping means is urged to a clampingposition and said gripping means is urged to a gripping position whensaid control valve is in said momentary position. 11. The stock-feedingapparatus recited in claim 10, and further comprising:

fluid-pressure-operated energy-absorbing means mounted between saidstationary body and said feed head, said energy-absorbing means beingoperable between energyabsorbing and retracted positions. 12. Thestock-feeding apparatus recited in claim 11, wherein:

said energy-absorbing means includes a double-acting differential pistonassembly having its forward side connected to said first operative sideof said apparatus and its rearward side connected to said secondoperative side of said apparatus; whereby said energy-operative means isnormally urged to said energy-absorbing position, alternatively urged tosaid retracted position and urged to said energy-absorbing position whensaid control valve is in said momentary position. 13. The stock-feedingapparatus recited in claim 9, and further comprising:

means for continuously biasing said control valve toward said normalposition.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,580/4-49 Dated May 25 1971 Inventor(g) Michael J. Chaban, Jr.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 3, line 25, "resets" should read --rests-;

line 37, change "45" to --44.--;and insert thereafter --Bearing 24closes the forward end of bore 35 and is sealed about shaft 13 by meansof glide ring 45--.

Column 4, line 6, after "justing" insert --rod--;

line 53, insert a period after "thereof".

Column 5, line 9, ore should read --bore--;

" should read --bore--;

line 35, "ore" should read --bore--;

- Page 1 of 3 Pages FORM PO-lOSO (10-69) USCOMM-DC 60375-P59 fl UYSGOVERNMENT PRINTING OFFICE I969 O366-33l Patent No.

Inventor(s) Column Column Column Column UNITED STATES PATENT OFFICEDated May 25 1971 Michael J. Chaban, Jr.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

line 44, "ore" should read --bore--;

line 61, "earing" should read --bearing--;

line 62, after "with" insert --extension 175 which operates in the samemanner as--;

line 70, "ore" should read --bore--.

line 8, "roper" should read --proper--;

line 45, "ore" should read --bore--;

line 59, "412" should read --l2--.

line 29, after "position," insert -stock gripping piston 151 is biasedupward to a closed position,--.

line 63, "raking" should read -braking--.

line 27, "109" should read --lO8-;

line 33, after "151" insert --and--;

line 45, after "urged" delete "downward feed";

- Page 2 of 3 Pages F ORM PO-105OHO-69] USCOMM-DC 6037G-PG9 Q U 5GOVERNMENT PRINTING OFFICE: Ill! O-35$-33 Patent No.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Dated May 25, 1971Inventor(s) Michael J. Chaban, Jr.

Column Column Column Column It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

line 46, delete "head is urged".

line

line

line

line

line

line

line

line

line

line

Signed and "stoke" should read --stroke--;

"224" should read -244--;

"heads" should read --head,--.

after "to" insert --a--.

- Page 3 of 3 Pages sealed this 23th day of March 1 972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. Attesting Officer FORM PO-105O (IO-69) ROBERTGOT'ISCHALK Commissioner of Patents USCOMM'DC GO376-P69 US GOVERNMENTPRINTING OFFICE: l9! OSEO-3SI

1. A stock-feeding apparatus operable through alternate feed and indexing strokes for incrementally feeding stock to a workperforming machine in synchronism with the operating cycle thereof, said stock-feeding apparatus being powered by a fluid prime mover and comprising: a stationary body; a feed head; means for connecting said feed head to said stationary body for reciprocal rectilinear motion with respect thereto; fluid-pressure operated means for controlling the rectilinear motion of said feed head; fluid-pressure-operated energy-absorbing means mounted between said stationary body and said feed head, said energy-absorbing means being operable between energy-absorbing and retracted positions; and means including a control valve for controlling the application of fluid pressure to said means for controlling the rectilinear motion of said feed head and to said energy-absorbing means; said control valve providing fluid pressure to said energyabsorbing means in timed relationship with the fluid pressure applied to said means for controlling the rectilinear motion of said feed head so that said energy-absorbing means absorbs the kinetic energy of said feed head through an incremental distance of the travel of said feed head at the end of said feed stroke.
 2. The stock-feeding apparatus recited in claim 1, wherein: said control valve provides fluid pressure to urge said energy-absorbing means to said energy-absorbing position while providing fluid pressure to said means for controlling the rectilinear motion of said feed head to urge said feed head in a feeding direction; and said control valve provides fluid pressure to urge said energy-absorbing means to said retracted position while providing fluid pressure to said means for controlling the rectilinear motion of said feed head to urge said feed head in an indexing direction.
 3. The stock-feeding apparatus recited in claim 2, wherein: said stationary body is formed with a cylinder therein; said energy-absorbing means includes a double-acting piston mounted in said cylinder and a rod attached to said piston adapted to protrude rearwardly from said cylinder toward said feed head.
 4. The stock-feeding apparatus recited in claim 3, wherein: said stationary body if formed with an orifice communicating the pressure from said control valve with the forward end of said cylinder; said energy-absorbing means is urged to said energy-absorbing position when fluid pressure is supplied to said cylinder forward of said piston; the kinetic energy of said feed head is absorbed by compression of the fluid in said cylinder and the release of said fluid through said orifice, the cross-sectional area of said orifice being so related to the cross-sectional area of said cylinder that a substantial portion of the kinetic energy of said feed head is absorbed during the time required for the excess pressure in said cylinder to be released through said orifice.
 5. A stock-feed apparatus operable through alternate feed and indexing strokes for incrementally feeding stock to a work-performing machine in synchronism with the operating cycle thereof, said stock-feeding apparatus being powered by a fluid prime mover and comprising: a stationary body; a feed head; means for connecting said feed head to said stationary body for reciprocal rectilinear motion with respect thereto; fluid-pressure-operated means for controlling the rectilinear motion of said feed head; fluid-pressure-operated stock-gripping means mounted on said feed head and movable between gripping and releasing positions, said stocK-gripping means being normally in said gripping position; means including a control valve for controlling the application of fluid pressure to said stock-gripping means in timed relationship with the fluid pressure applied to said means for controlling the rectilinear motion of said feed head; and a release valve for selectively moving said stock-gripping means to said releasing position, said release valve being movable between open and closed positions and being normally urged to said closed position by said fluid pressure, said release valve being formed with a hole therethrough the transmit fluid pressure to said stock-gripping means from said control valve when in said normally closed position; said release valve being shaped and configured to interrupt the supply of fluid pressure from said control valve to said stock-gripping means and to exhaust fluid pressure from said stock-gripping means when in said open position.
 6. A stock-feeding apparatus operable through alternate feed an indexing strokes for incrementally feeding stock to a work-performing machine in synchronism with the operating cycle thereof, said stock-feeding apparatus being powered by a fluid prime mover and comprising: a stationary body; a feed head; means for connecting said feed head to said stationary body for reciprocal rectilinear motion with respect thereto; fluid pressure operated means for controlling the rectilinear motion of said feed head; fluid-pressure-operated stock-gripping means mounted on said feed head and movable between gripping and releasing positions; fluid-pressure-operated stock-clamping means mounted on said stationary body and movable between clamping and releasing positions; and means including passageways defining first and second operative sides of said apparatus and a control valve for controlling the application of fluid pressure through said passageways to said means for controlling the rectilinear motion of said feed head, to said stock-gripping means and to said stock-clamping means; said control valve providing fluid pressure alternately to said first and second operative sides and cooperatively with said passageways providing fluid pressure in timed relationship to said fluid-pressure-operated stock-gripping, clamping and rectilinear-motion-controlling means; said control valve providing fluid pressure to said first operative side when in a first position and providing fluid pressure to said second operative side when in a second position; said control valve further simultaneously applying fluid pressure to both said first and second operative sides when in a momentary position, said control valve passing through said momentary position each time it passes between said first and second positions.
 7. The stock-feeding apparatus recited in claim 6, wherein: said stationary body is formed with a control valve bore therein; and said control valve is a four-way valve mounted for longitudinal movement in said bore and connected with said passageways.
 8. The stock-feeding apparatus recited in claim 7 wherein: said control valve includes a stem mounted one end thereof and a cap telescopically mounted on said stem, said stock-feeding apparatus further comprising: first means for continuously biasing said control valve to said first position; and second means for biasing said cap away from said control valve, said second biasing means being stronger than said first biasing means; said cap being contacted by said work-performing machine during its work-performing cycle so as to move said control valve from said first position through said momentary position to said second position, said work-performing machine then continuing movement in the same direction to perform work on said stock, thereby telescoping said cap on said stem toward said control valve, said work machine then retracting from the vicinity of said stock before said control valve returns to said firSt position to initiate another cycle of said stock-feeding apparatus.
 9. A stock-feeding apparatus operable through alternate feed and indexing strokes for incrementally feeding stock to a work-performing machine in synchronism with the operating cycle thereof, said stock-feeding apparatus being powered by a fluid prime mover and comprising: a stationary body; a feed head; means for connecting said feed head to said stationary body for reciprocal rectilinear motion with respect thereto; fluid-pressure-operated means for controlling the rectilinear motion of said feed head; fluid-pressure-operated stock-gripping means mounted on said feed head and movable between gripping and releasing positions; fluid-pressure-operated stock-clamping means mounted on said stationary body and movable between clamping and releasing positions; and means including passageways defining first and second operative sides of said apparatus and a control valve for controlling the application of fluid pressure through said passageways to said means for controlling the rectilinear motion of said feed heads to said stock-gripping means and to said stock-clamping means; said control valve providing fluid pressure alternately to said first and second operative sides and cooperatively with said passageways providing fluid pressure in timed relationship to said fluid-pressure-operated stock-gripping, clamping and rectilinear-motion-controlling means; said stationary body being formed with a control valve bore therein, said control valve being a four-way valve mounted for longitudinal movement in said bore and connected with said passageways; said control valve being formed with a first port connected to said first operative side of said apparatus, a second port connected to said second operative side, a fluid pressure port and an exhaust port; said control valve having normal and alternate main positions and a momentary position, said control valve passing through said momentary position when changing from one main position to the other; said control valve normally connecting said fluid pressure port to said first port and said exhaust port to said second port, and alternately connecting said fluid pressure port to said second port and said exhaust port to said first port; said control valve connecting said fluid pressure port to both said first and second ports when in said momentary position.
 10. The stock-feeding apparatus recited in claim 9 wherein: said means for controlling the rectilinear motion of said feed head includes a double-acting piston assembly having its forward side connected to said first operative side of said apparatus and its rearward side connected to said second operative side of said apparatus; said stock-gripping means includes a double-acting differential piston assembly having its lower side connected to said first operative side of said apparatus and its upper side connected to said second operative side of said apparatus; said stock-clamping means includes a double-acting differential piston assembly having its upper side connected to said first operative side of said apparatus and its lower side connected to said second operative side of said apparatus; whereby said feed head is normally urged in a feeding direction, said gripping means is normally urged to a gripping position and said clamping means is normally urged to releasing position; whereby said feed head is alternately urged in an indexing direction, said gripping means is alternately urged to a releasing position and said clamping means is alternately urged to a clamping position; and whereby said feed head remains stationary, said clamping means is urged to a clamping position and said gripping means is urged to a gripping position when said control valve is in said momentary position.
 11. The stock-feeding apparatus recited in claim 10, and further comprising: fluid-pressure-operated energy-absorbing Means mounted between said stationary body and said feed head, said energy-absorbing means being operable between energy-absorbing and retracted positions.
 12. The stock-feeding apparatus recited in claim 11, wherein: said energy-absorbing means includes a double-acting differential piston assembly having its forward side connected to said first operative side of said apparatus and its rearward side connected to said second operative side of said apparatus; whereby said energy-operative means is normally urged to said energy-absorbing position, alternatively urged to said retracted position and urged to said energy-absorbing position when said control valve is in said momentary position.
 13. The stock-feeding apparatus recited in claim 9, and further comprising: means for continuously biasing said control valve toward said normal position. 